21211008 has 128 divisors (see below), whose sum is σ = 69457920. Its totient is φ = 5584896.

The previous prime is 21210989. The next prime is 21211009. The reversal of 21211008 is 80011212.

It is a tau number, because it is divible by the number of its divisors (128).

It is a cake number, because a cake can be divided into 21211008 parts by 503 planar cuts.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211009) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 34641 + ... + 35247.

It is an arithmetic number, because the mean of its divisors is an integer number (542640).

Almost surely, 2^21211008 is an apocalyptic number.

21211008 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21211008, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34728960).

21211008 is an abundant number, since it is smaller than the sum of its proper divisors (48246912).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21211008 is a wasteful number, since it uses less digits than its factorization.

21211008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 644 (or 632 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 15.

The square root of 21211008 is about 4605.5410105654. The cubic root of 21211008 is about 276.8133955004.

The spelling of 21211008 in words is "twenty-one million, two hundred eleven thousand, eight".